First off, you'll need a C++ compiler (I use Code::Blocks). You'll also need the Plugin SDK, which is included with the latest version of RB. Here is a step-by-step walkthru of how I created the famous "add5" plugin. Note that I created a Windows plugin. If you're working on a different platform, then some of these steps will be different, though the overall procedure is the same.

Start up Code::Blocks.

File>New>Project…Select Dynamic Link Library icon and click [Go].Type in name for project, select where to save it, release version only.

Double click WinHeader++.h, change line 37 to “#ifdef IGNOREQT”, File>Save, then remove WinHeader++ tab from editor. Note that I used this procedure to get the compiler to ignore quicktime, which is needed on Windows. I'm sure I'll get raked over the coals for this, but it worked for me.

File>SaveBuild>Build (making sure that the build target is Release and not Debug).The DLL file will be located at: project file folder>bin>Release>filename.dll

Exit Code::Blocks.

Goto Plugins SDK>Plugin Converter. There are two RB project files there (Plugin Converter and Plugin Creator). Use REALbasic to compile both of those projects. Place PluginConverter.exe into the Plugin Creator folder that RB made when it compiled the Plugin Creator project.